Daniel_Stuckey writes: It hopefully doesn't come as a surprise that your friends shape who you are. But we tend to think of that on a micro level: If your close circle of friends tends to have tattoos, wear polo shirts, or say "chill" a lot, it's quite possible that you'll emulate them over time—and they'll emulate you too.

But what happens on a macro scale, when your friend circle doesn't just include the dozen people you actually hang out with regularly, but also the hundreds or thousands of acquaintances you have online? All of those feeds may seem filled with frivolities from random people (and they are!) but that steady stream of life updates—photos, rants, slang—are probably shaping you more than you think.